Role of Adenosine in Atrial Fibrillation
Adenosine is contraindicated and potentially harmful in atrial fibrillation and should not be used for this rhythm. 1
Why Adenosine Should Be Avoided in AF
Adenosine does not terminate atrial fibrillation and can cause dangerous complications, particularly in patients with pre-excitation syndromes. The major guidelines explicitly state that adenosine is not recommended for AF management 1:
- In pre-excited atrial fibrillation (Wolff-Parkinson-White syndrome), adenosine can cause paradoxical acceleration of ventricular rate and precipitate ventricular fibrillation, which is potentially fatal 1, 2
- The FDA drug label warns that adenosine can induce atrial fibrillation as an adverse effect, with episodes lasting 15 seconds to 6 hours 2
- AV nodal blocking agents like adenosine are specifically contraindicated in wide-complex irregular rhythms suggestive of pre-excited AF 1
The Diagnostic Confusion Problem
Adenosine is frequently misused for atrial fibrillation due to misdiagnosis of the rhythm on ECG. A prospective study found that:
- 32% of hospitalized patients who received adenosine actually had atrial fibrillation, not supraventricular tachycardia 3
- 31% of internal medicine house officers misdiagnosed rapid atrial fibrillation as paroxysmal supraventricular tachycardia on 12-lead ECG 3
- This misuse results in unnecessary expenses and risk of adverse effects including proarrhythmia (2% incidence of asystole and polymorphic ventricular tachycardia) 3
When Adenosine IS Appropriate (Not AF)
Adenosine is highly effective for regular narrow-complex tachycardias involving the AV node, such as:
- AVNRT (AV nodal reentrant tachycardia): 95% termination rate 4
- AVRT (AV reentrant tachycardia): 90-95% success rate 1, 4
- Initial dose: 6 mg IV push via proximal vein, followed by 20 mL saline flush 4
- If no conversion in 1-2 minutes: 12 mg IV push, may repeat once 4
Mechanism of Adenosine-Induced AF
When adenosine does induce atrial fibrillation (as a complication), it occurs through a specific mechanism:
- Adenosine causes atrial premature complexes that trigger AF via a "long-short" atrial sequence 5
- Incidence of adenosine-induced AF during electrophysiology studies: 12% 5
- During pharmacologic stress testing: 0.41% incidence 6
- Most episodes are self-limited and convert spontaneously to sinus rhythm 2, 6
Critical Safety Considerations
Resuscitation equipment must be immediately available when administering adenosine because:
- Fatal and nonfatal cardiac arrest, sustained ventricular tachycardia, and myocardial infarction have occurred 2
- Ventricular fibrillation can occur even in structurally normal hearts without accessory pathways 7
- Defibrillator must be available, especially when Wolff-Parkinson-White syndrome is a consideration 4, 2
Correct Management of AF Instead
For atrial fibrillation with rapid ventricular response, use rate control agents, not adenosine:
- IV beta-blockers or non-dihydropyridine calcium channel blockers (diltiazem, verapamil) are first-line for rate control in stable patients 1
- Immediate synchronized cardioversion for hemodynamically unstable patients 1
- Digoxin and amiodarone for rate control in patients with heart failure 1
The key distinction: adenosine works for regular narrow-complex tachycardias (AVNRT/AVRT), not for the irregular rhythm of atrial fibrillation. 1, 4, 3